Polk Sheriff Grady Judd said the boys were missing for about 10 to 15 minutes before family members realized they were gone. The children's relatives began frantically searching for the pair and found them floating face down behind Nelson and Vickie Lugo's Lakeland home at about 6:15 p.m., Judd said.

"At this point in the investigation, it appears to be nothing more than a tragic, tragic accident," Judd said.

Neighbors watched as deputies entered and left the two-story home. At one point a small child was carried out of the house and handed to family members, The Ledger reported.

The pool is about 5-feet deep and had a fence around it, but it appears the gate was open, Judd said. The house's back door also has a latch that can be easily pushed open.

"It certainly would be no challenge at all for an 18-month-old and a 24-month-old to push the door open," Judd said.

Judd said the investigation is preliminary but that no charges were expected to be filed.